md: don't require sync_min to be a multiple of chunk_size.

There is really no need for sync_min to be a multiple of
chunk_size, and values read from here often aren't.
That means you cannot read a value and expect to be able
to write it back later.

So remove the chunk_size check, and round down to a multiple
of 4K, to be sure everything works with 4K-sector devices.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 0d89685..3724a29 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4427,7 +4427,6 @@ min_sync_store(struct mddev *mddev, const char *buf, size_t len)
 {
        unsigned long long min;
        int err;
-       int chunk;
 
        if (kstrtoull(buf, 10, &min))
                return -EINVAL;
@@ -4441,16 +4440,8 @@ min_sync_store(struct mddev *mddev, const char *buf, size_t len)
        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
                goto out_unlock;
 
-       /* Must be a multiple of chunk_size */
-       chunk = mddev->chunk_sectors;
-       if (chunk) {
-               sector_t temp = min;
-
-               err = -EINVAL;
-               if (sector_div(temp, chunk))
-                       goto out_unlock;
-       }
-       mddev->resync_min = min;
+       /* Round down to multiple of 4K for safety */
+       mddev->resync_min = round_down(min, 8);
        err = 0;
 
 out_unlock: